Method for additive manufacturing of a 3D item by means of fused deposition modeling and additive manufacturing apparatus

Abstract

The invention relates to a method and an apparatus (1) for additive manufacturing of a 3D item (2) by means of fused deposition modeling of a composite material, whereby the composite material is fed through a heated printer extruder head (4) and deposited on a printer bed (3) as a layer arrangement that form the 3D item (2). The composite material is provided as at least one rigid rod (10) that is conveyed out of a rod magazine (9) that is capable of storing at least one rigid rod (10). The rigid rod (10) is then conveyed through a guide tube (15) that is arranged within the printer extruder head (4), whereby the rigid rod (10) is heated during the conveyance through the guide tube (15), and whereby the heated and viscous composite material is discharged through a discharge nozzle (16) at one end of the guide tube (15) and deposited as the layer arrangement onto the printer bed (3) to generate the 3D item (2).

Description

[0001] Method for additive manufacturing of a 3D item by means of fused deposition modeling and additive manufacturing apparatus

[0002] Technical Field

[0003] The present invention relates to a method for additive manufacturing of a 3D item by means of fused deposition modeling of a composite material, whereby the composite material is fed through a heated printer extruder head and deposited on a printer bed as a layer arrangement that form the 3D item. The present invention also relates to an additive manufacturing apparatus for additive manufacturing of a 3D item by means of fused deposition modeling of a composite material, the additive manufacturing apparatus comprising a printer extruder head for discharging and depositing the heated composite material as the layer arrangement on a printer bed to generate the 3D item out of the composite material, whereby the discharging and depositing of the heated composite material can be controlled by a control device, the additive manufacturing apparatus further comprising a heating device for heating the composite material prior to discharging the heated composite material out of the printer extruder head.

[0004] State of the Art

[0005] Additive manufacturing of 3D items allows for almost instantaneous manufacture of 3D items of almost any shape or composition of material. Furthermore, additive manufacturing does not require the preceding production of a tool form, which is costly and time consuming, but allows for cheap manufacture of a large number of 3D items. However, some shapes of 3D items cannot be manufactured by using tool forms, e.g. due to undercuts or internal formations that cannot be created by a tool form. Thus, additive manufacturing is very attractive for the manufacture of individual 3D items or of small batches of 3D items with either different or complex shape or composition. Furthermore, additive manufacturing allows for the manufacture of 3D items with shapes that cannot be manufactured by other means or methods, e.g. by injection molding or cutting.

[0006] There are several different methods of additive manufacturing known in the prior art. Powder molding or selective laser sintering is performed by selectively heating a small spot of powder particles that melt and fuse to form a part of the 3D item. By consecutively fusing a number of such small spots into a layer of the desired shape and a layer arrangement into a large object, a 3D item can be manufactured. However, for each layer a powder bed must be provided, which usually limits this method to making use of the same composition of powder for each layer. Furthermore, the precision of manufacture is limited by the precision that can be achieved for the selective heating and melting of a small spot of powder.

[0007] Another method that can be used for additive manufacturing is fused deposition modeling. Usually, a thermoplastic filament is fed into a heated printer extruder head, the filament is heated and melted within the printer extruder head, and then extruded layer-wise from the printer extruder head on a printer bed. Many parameters like e.g. flow geometry of the extruder, heating method and the melt flow behavior of the heated and viscous composite material affect the deposition of layers and the manufacture of the 3D item as a layer arrangement of composite material extruded by the printer extruder head. By changing the thermoplastic filament during manufacture of a single 3D item it is possible to generate a 3D item that comprises two or more regions of different materials. However, the precision of the manufactured 3D item is limited by the flow characteristics of the heated and viscous composite material that will be affected by many parameters like e.g. the temperature of the printer extruder head or the printer bed, the conveyance of composite material through the printer extruder head or even ambient temperature and alignment of the printer bed with respect to the printer extruder head.

[0008] Recent developments constantly improve the speed and precision of the additive manufacturing of 3D items. However, some composite materials are challenging for the production of homogeneous filaments with characteristics that allow for an easy and precise performance of fused deposition molding. Furthermore, for some 3D items the fused deposition molding imposes either limitations or at least a severe burden on efforts that are required to achieve the desired precision of manufacture.

[0009] Thus, there is a need for a method that allows for rapid and precise manufacturing of a number of 3D items, especially from materials usually considered problematic for fused deposition molding. Furthermore, there is a need for an advantageous method to generate a pharmaceutical solid administration form as a 3D item. In addition, there is a need for an advantageous manufacturing apparatus, in particular for rapid and precise manufacturing of 3D items, and in particular pharmaceutical solid administration forms.

[0010] Summary of the Invention

[0011] The present invention discloses a method for additive manufacturing of a 3D item by means of fused deposition modeling and additive manufacturing apparatus, characterized in that the composite material is provided as at least one rigid rod that is conveyed out of a rod magazine that is capable of storing at least one rigid rod, and in that the rigid rod is then conveyed through a guide tube that is arranged within the printer extruder head, whereby the rigid rod is heated during the conveyance through the guide tube, and whereby the heated and viscous composite material is discharged through a discharge nozzle at one end of the guide tube and deposited as the layer arrangement onto a platform to generate the 3D item. Some materials like metals or e.g. brittle composite materials cannot be easily processed into elastic filaments. By making use of rigid rods instead of a virtually endless filament for the fused deposition molding, the range of materials that are suitable for performing the fused deposition modeling is significantly increased. Also, for some other materials and in particular for some composite materials comprising active pharmaceutical ingredients the preparation of rigid rods is significantly simpler and allows for more effective composite materials compared to the preparation of elastic filaments that can be used to perform fused deposition molding, as the rigid rods do not require being elastic enough to be stored and deployed from a roll of filament. Thus, this method can be used very advantageously for the additive manufacturing of pharmaceutical solid administration forms like e.g. tablets with individual composition and dosage of one or more pharmaceutical active ingredients. A pharmaceutical solid administration form may also be referred to as a pharmaceutical solid administration dosage form herein.

[0012] In particular for the additive manufacturing of pharmaceutical solid administration forms, it is considered very advantageous to be able to use rigid rods made of or comprising e.g. polyethylene glycol (PEG), polyethylene oxide (PEG), polyethylene oxide esters and ethers, poloxamers, polyvinyl alcohol (PVA), polyvinyl acetate(PVAc), polyvinylpyrrolidone (PVP), vinylpyrrolidone-vinyl acetate copolymer (VA), polycaprolactone (PCL), polylyvinyl caprolactam-polyvinyl acetate-polyethyleneglycol graft co-polymer, cellulose and its derivatives, such as hydroxypropyl methylcellulose (HPMC), hydroxyethylcellulose (HEC), ethyl cellulose (EC), hydroxypropyl cellulose (HPC), hydroxypropyl methylcellulose phthalate (HPMCP), hydroxypropylmethylcellulose acetate succinate (HPMCAS), acrylic and methacrylicpolymers, waxes, polylactic acid (PLA), poly(lactic-co- glycolic acid) (PLGA), sucrose fatty acid esters gelatin, alginate, shellac, agar or shellac, or any composites comprising mixtures and blends thereof.

[0013] Furthermore, the conveyance of a preset length of a segment of a rigid rod that is extruded through the printer extruder head can be controlled and monitored more precisely than a given length of a segment of a filament, as there is an end face of the rigid rod that can be used e.g. for pushing the rigid rod through the guide tube and for determining any displacement of the end face, which in turn can be used for deducing the length of the segment of the rigid rod that has been conveyed into and through the guide tube. Thus, by using rigid rods the additive manufacturing of the 3D item can be performed with high precision. As several rigid rods can be stored within the rod magazine, making use of more than one rigid rod for the manufacture of a 3D item is facilitated and does not require any manual interaction for e.g. providing and feeding a following rigid rod to the printer extruder head after the previous rigid rod has been fully conveyed through and extruded from the printer extruder head. The rod magazine can be designed to be able to (configured to) simultaneously store many similar rigid rods that can be successively ejected from the rod magazine and fed into the guide tube. It is also possible to store two or more different kinds of rigid rods within the rod magazine that allows for the manufacture of a 3D item with two or more different materials without the need for a manually or automatically performed change of composite material supply or switch of rod magazines.

[0014] Within the context of this invention, a layer arrangement that forms the 3D item may comprise only a few layers or even only one single layer. For most applications, the layer arrangement comprises at least two or several layers, usually more that 5 to 10 layers, and sometimes a large number of layers, i.e. more than 50 or 100 layers.

[0015] Within the context of this invention, a rod is considered being a rigid rod if the rigid rod does not undergo any appreciable elastic or plastic deformation when the usual mechanical forces are applied that are necessary for the required displacement of the unheated rigid rod out of the rod magazine and through the guide tube of the printer extruder head. Thus, suitable composite materials may also comprise polylactic acid or polyvinyl alcohols.

[0016] However, a rigid rod preferably has a straight-line shape. Also, according to a preferred embodiment, a rigid rod has a length along the longitudinal axis of the rigid rod of less than 1 m, preferably less than 0.5 m and most preferred less than 0.3 m. A rigid rod is not deformed during the storage of the rigid rod within the rod magazine. Furthermore, a rigid rod retains its shape and will not be deformed during removal from the rod magazine and conveyance through the guide tube of the printer extruder head until heating of the rigid rod results in liquefaction or plasticization of the heated composite material of the rigid rod.

[0017] According to an embodiment of the invention, a rigid rod is preferably made of a material which shows brittle fracture on a 3-point bending test setup with support spaced 30 mm and with a typical diameter of the rigid rod of 1 .75 mm. These materials show strain at break of < 3% at stresses of around 50 MPa. More specifically, the rigid rod is preferably made of a material wherein the strain at break is within a range of approx. 1.25 % at stresses of approx. 50 MPa up to approx. 2.5 % at stresses of approx. 80 MPa. Such a 3-point bending test setup is disclosed in more detail in Gottschalk, Nadine; Bogdahn, Malte; Harms, Meike; Quodbach, Julian (2021 ): Brittle polymers in Fused Deposition Modeling: An improved feeding approach to enable the printing of highly drug loaded filament. In: International Journal of Pharmaceutics 597, S. 120216. DOI:

[0018] 10.1016 / j. ijpharm .2021 .120216, the entire contents of which are included by reference herein.

[0019] In contrast thereto, materials that are well-known in the prior art and specifically made for filament based fused deposition modelling do not fracture under these conditions, but show plastic deformation.

[0020] Furthermore, rigid rods are preferably linear rods, i.e. linearly shaped rods with a straight longitudinal axis. Without external force, the rigid rods retain their straight line. Rigid rods may also have a curved course of the longitudinal axis, which is also maintained without external forces, whereby the curved course is maintained during insertion into the magazine, during feeding into the printer extruder head and until melting and removal from the printer extruder head.

[0021] It is considered favorable for many applications that a cross-sectional area of the rigid rods is circular or quadratic. However, it is also possible to make use of rigid rods with a different cross-sectional area. A rigid rod may have any length that is feasible for storing the rigid rod within the rod magazine. For many applications, rigid rods with a length between 5 cm and 30 cm and preferably between 10 cm and 20 cm are considered advantageous. In order to allow for a precise handling and in particular for a precise discharge of the rigid rods out of the printer extruder head, the specified dimensions of the rigid rods should be met as precisely as possible during manufacture of the rigid rods.

[0022] The rod magazine can be designed as a revolver magazine, e.g. with a rotating drum or as a cassette magazine comprising one or more cassettes that can be permanently or removably mounted within a rod magazine housing. The rod magazine may have linear dimensions or a diameter of 5 cm to 30 cm and preferably between 10 cm and 20 cm. The rod magazine can be designed for storing a single rigid rod or just a few rigid rods. Preferably, the rod magazine is capable of storing at least two rigid rods or several rigid rods. For many applications it is considered advantageous if the rod magazine is capable of storing many rigid rods like e.g. 50 or 100 or more rigid rods.

[0023] According to a favorable aspect of the invention, the rigid rod is pushed out of the rod magazine with a piston that is displaced along a rod axis of the rigid rod. The piston can be used to positively engage with the end surface of the rigid rod that is pressed out of a corresponding rod storage pocket that is arranged within the rod magazine. Thus, the displacement of the rigid rod can be precisely specified and performed. Due to the positive engagement of the piston with the end face of the rigid rod, there is no risk of any slack or uncontrolled slip during the displacement of the rigid rod.

[0024] In yet a similar embodiment of the invention, the rigid rod is conveyed through the guide tube by either displacing a piston or a subsequently conveyed following rigid rod along a guide tube axis of the guide tube. Displacing the rigid rod through the guide tube by means of a piston provides for the same advantages as displacing the rigid rod out of the rod magazine by means of a piston. In case that more than one rigid rod is required to complete the manufacturing the 3D item, after feeding the first rigid rod out of the rod magazine and into the guide tube, this first rigid rod can be followed by a following rigid rod. Said following rigid rod can be subsequently pressed out of the rod magazine by a piston or some other appropriate displacement means in such a manner that the front face of the following rigid rod positively engages with the end face of the first rigid rod that is conveyed through the guide tube, which allows for the following rigid rod to push the first rigid rod in front of itself and through the guide tube as the following rigid rod enters the guide tube and is pressed through the guide tube.

[0025] It is considered an advantageous option that the rod magazine comprises means for contamination protection for each rigid rod that is stored within the rod magazine, whereby before conveying the rigid rod out of the rod magazine the respective means for contamination protection that correspond to said rigid rod are breached or removed to allow for accessing and removing said rigid rod out of the rod magazine. Thus, each rigid rod can be stored within the rod magazine without any risk of contamination during storage or subsequent use of the rod magazine. Furthermore, by providing air-tight means for contamination protection, the risk of unwanted degradation or alteration of rigid rods due to the environmental conditions can be significantly reduced, resulting in longer stability of storage of the rigid rods within the rod magazine. The means for contamination protection can be designed to also provide for a tamper-evident sealing of each of the rigid rods that is stored within the rod magazine.

[0026] According to another favorable aspect of the invention, the heating of the rigid rod is performed by heating the guide tube at or near the discharge nozzle by means of a heating device that is arranged in a heat transmitting contact with the guide tube. Thus, there is no direct contact between the heating device and the rigid rod that might result in unwanted contamination of the rigid rod. Furthermore, there will be no risk of any residual rigid rod material that might remain on a heating surface of the heating device. The heating device can be arranged and operated so as to heat up the rigid rod during the displacement through the guide tube in such a manner that the rigid rod will have the required viscous condition to be properly extruded through the discharge nozzle of the guide tube and out of the printer extruder head.

[0027] In order to avoid a premature heating of the rigid rod that might interfere with a precise displacement of the rigid rod through the guide tube or with a precise heat uptake of the rigid rod to become viscous before being extruded out of the printer extruder head, the guide tube is cooled at a distance to the discharge nozzle in order to prevent a premature heating of the rigid rod that is conveyed through the guide tube. The cooling of the guide tube can be performed by any suitable means and methods, like e.g. using a heat pipe or a Peltier element. Thus, the section of the guide tube that is heated by the heating device is limited by the cooling device that cools an entry section of the guide tube and thus the rigid rods until they are conveyed through a heated section of the guide tube just before being discharged out of the discharge nozzle of the guide tube.

[0028] Unless the 3D item is very small or the corresponding rigid rod is quite large, it may be necessary that more than one rigid rod required to fully generate the 3D item by fused deposition molding. In an advantageous embodiment of the idea of the invention, in order to convey a following rigid rod after the rigid rod through the guide tube, the rod magazine is relocated or manipulated in such a manner as to arrange the following rigid rod next to an entry opening of the guide tube and to convey the following rigid rod through an entry opening of the guide tube into the guide tube. Arranging the following rigid rod next to an entry opening of the guide tube can be performed e.g. by either moving the rod magazine in such a manner that another rod storage element within the rod magazine is arranged next to the entry opening, or by moving a movably mounted inner part like e.g. a magazine tray of the rod magazine that comprises at least one rod storage element into a position that allows for a displacement of the rigid rod that is stored within said rod storage element out of the rod magazine and through the entry opening of the guide tube into the guide tube. Such a relocation or manipulation of the rod magazine can be manually performed. However, in order to allow for a rapid manufacture of a large 3D item or of many small 3D items that requires more than one rigid rod, the required relocation or manipulation of the rod magazine is automatically performed and operated by a rod magazine controller.

[0029] According to yet another aspect of the invention, the guide tube is removed and a clean following guide tube is inserted into the printer extruder head before conveying a following rigid rod out of the rod magazine and through the following guide tube. It is also possible that the discharge nozzle of the printer extruder head can be removed and can be replaced with a clean discharge nozzle before conveying a following rigid rod out of the rod magazine or through the guide tube. Replacing the guide tube by a new guide tube or by a fully cleaned guide tube will eliminate any risk of cross contamination of two rigid rods made of different composite materials that are consecutively conveyed through the guide tubes. Thus, in case that manufacturing a 3D item requires a change of material during the fused depositing molding process in order to generate different parts or regions of the 3D item out of different materials, by changing the guide tube any residual material that might adhere to the guide tube will be removed from the printer extruder head. After removal, the removed guide tube can be processed and cleaned in order to be inserted again into the printer extruder head. It is also possible to change the material between two successive manufactures of two different 3D items. The possible removal of the guide tube also eliminates the need for a cleaning step performed on the complete printer extruder head in between the conveyance of two different rigid rods through the same guide tube, which will increase the manufacturing speed of either a single 3D item or of a series of 3D items. In case that the discharge nozzle is not designed as an integral part of the guide tube, the discharge nozzle can be removed and replaced by a clean discharge nozzle in order to reduce any unwanted contamination of the composite material that will be discharged from the printer extruder head during the manufacture of a 3D item. Furthermore, according to an advantageous embodiment of the invention, it is also possible that the piston is removed and a clean following piston is used for pressing a following rigid rod out of the rod magazine. Thus, all parts of the additive manufacturing apparatus that will be in direct contact with the composite material during a manufacturing process of a 3D item can be replaced by clean parts, either on a regular basis or if need arises. Such a replacement can be performed automatically or manually. The replacement of these parts significantly reduces any unwanted risk of contamination of a 3D item without the need for and the additional burden of performing a cleaning process of the additive manufacturing apparatus.

[0030] Even though the displacement of rigid rods through the guide tube can be specified and monitored precisely as disclosed above, it might be advantageous to also provide additional means for detecting and monitoring the generation of the 3D item by other means. Thus, according to an advantageous embodiment of the invention, a total weight of the layer arrangement that has been deposited on the printer bed is measured before conveying a following rigid rod out of the rod magazine and through the following guide tube. Such a weight measurement can be performed at any time during the manufacture of the 3D item. However, in order to reduce any unwanted interference of appropriate heating of the rigid rod within the guide tube or of extruding the heated and viscous rigid rod out of the discharge nozzle of the guide tube, a weight measurement is performed preferably after a rigid rod has been fully discharged out of the guide tube.

[0031] The weight measurement can be performed by any means or method that is considered suitable and sufficiently precise when performed within an additive manufacturing apparatus during the process of generating the 3D item by fused deposition molding. In order to reduce any risk of interfering with the manufacturing process of the 3D item it is considered advantageous to measure the weight of the printer bed and the layer arrangement already deposited on the printer bed by appropriate weighing means, and then to determine the weight of the 3D item as the difference between the measured value for the combination of printer bed and layer arrangement on the one hand and a previously or subsequently measured value for the weight of the printer bed on the other hand.

[0032] Due to the many advantages and benefits described above, and according to an advantageous aspect of this invention, the method is used to generate a pharmaceutical solid administration form as 3D item, wherein the pharmaceutical solid administration form comprises at least one active pharmaceutical ingredient. The use of additive manufacturing methods allows for manufacture of individual pharmaceutical solid administration forms like tablets at the point of care. Thus, a personalized tablet may be manufactured immediately before consumption by the patient. 3D printing of pharmaceutical solid administration forms provides for many advantages, including optimized dosage and dissolution characteristics of the active pharmaceutical ingredient for each patient and for each administration of a tablet, the use of individual binder agents adapted to needs or preferences of the respective patient, and individual shape and structure of the tablet resulting in a desired solubility of the tablet or different release properties of the pharmaceutical solid administration form. The design of a customizable pharmaceutical solid administration form like a tablet whose release is carefully controlled for individual patients and the generation on-demand using a well-known 3D printing process may support effective implementation of individualized therapy, resulting in improvements of currently applied therapy methods. However, the manufacture of individual pharmaceutical solid administration forms should be carefully monitored and controlled in order to minimize any health risks due to deviations of the manufactured pharmaceutical solid administration form from the manufacturing specifications like, e.g. any deviation of the content of the pharmaceutical ingredient or some unwanted cross contamination with residual pharmaceutical ingredients from a preceding manufacturing process. As the method described above allows for a very precise and contamination free manufacturing of a 3D item, this method can be used particularly advantageously for the production of small batches of individualized pharmaceutical solid administration forms. The present invention also relates to an additive manufacturing apparatus for additive manufacturing of a 3D item by means of fused deposition modeling of a composite material, the additive manufacturing apparatus comprising a printer extruder head for discharging and depositing the heated composite material as the layer arrangement on a printer bed to generate the 3D item out of the composite material, the additive manufacturing apparatus further comprising a heating device for heating the composite material prior to discharging the heated composite material out of the printer extruder head. Even though many different embodiments of such additive manufacturing apparatus are known and widely used, most embodiments do not comply with very strict specifications e.g. defined or recommended by standards like the Good Manufacturing Practices that apply for the manufacturing of pharmaceutical solid administration forms with active pharmaceutical ingredients. The present invention thus also relates to an additive manufacturing apparatus configured to carry out the method according to the present invention.

[0033] Thus, it is considered a further object of this invention to provide for an additive manufacturing apparatus that allows for a very precise and contamination free manufacturing of a 3D item and in particular of a pharmaceutical solid administration form comprising at least one active pharmaceutical ingredient.

[0034] The present invention discloses an additive manufacturing apparatus as previously described, characterized in that the additive manufacturing apparatus comprises a rod magazine that is capable of storing at least one rigid rod, in that the printer extruder head comprises a guide tube through which a rigid rod made of the composite material can be conveyed and heated by the heating device, and in that the additive manufacturing apparatus comprises a rod conveyance means for conveying a rigid rod out of the rod magazine and through the guide tube before discharging the heated and viscous composite material through a discharge nozzle at one end of the guide tube in order to deposit the discharged composite material as the layer arrangement on the printer bed to generate the 3D item. Making use of rigid rods instead of an elastic and virtually endless filament allows for the use of additional materials that either cannot be manufactured into elastic filaments or that require large efforts and additional components to be added into the composite material to enable the making of elastic and virtually endless filaments.

[0035] For some applications, e.g. for testing purposes, the rod magazine may be designed to only store a single rigid rod. However, usually it is considered advantageous that the rod magazine is capable of storing at least two rigid rods, preferably more than 50 rigid rods and most preferably more than 100 rigid rods. The rigid rods that are stored within the rod magazine may be identical in shape and material. It is also possible to provide for a design of the rod magazine that allows for storing different kind of rigid rods and in particular for storing rigid rods with different shape, length or cross-sectional area.

[0036] Due to the rod magazine and corresponding rod conveyance means it is possible not only to store several or even a large number of rigid rods within the additive manufacturing apparatus, but also to automatically feed a following rigid rod to the printer extruder head after the previously fed rigid rod has been conveyed through and extruded from the printer extruder head. This allows continuous extrusion of the heated composite material across multiple rigid rods that are fed sequentially from the rod magazine to the printer extruder head.

[0037] Furthermore, the displacement of the rigid rod can be precisely measured by e.g. optical measurement means determining the position of an end face of the rigid rod, or by measuring the operation of the rod conveyance means that results in a displacement of the rigid rod. Either continuously measuring the displacement of the rigid rod or measurements at intervals or after finalization of a 3D item allows for precise determination of the volume of the composition material that either is currently discharged or has been discharged and extruded from the printer extruder head. It is considered a very favorable option and aspect of the invention that the rod magazine may comprise means for contamination protection for each rigid rod that is stored within the rod magazine. The means for contamination protection can be a sealing film that covers the relevant parts of the rod magazine and protects the rigid rods that are stored within the rod magazine. Thus, the risk of any unwanted contamination of the rigid rods can be reduced and minimized. This also significantly improves the storage stability for a rod magazine that has been loaded with rigid rods. In case that each rigid rod is separately sealed and can be removed from the rod magazine without affecting the sealing of another rigid rod that is also stored within the rod magazine, this allows for a long term use of a rod magazine from which selectively some rigid rods can be removed, but other rigid rods can remain stored within the rod magazine without affecting the quality of the rigid rods that remain stored and unused for a long time.

[0038] Accordingly, it is possible that the rod magazine comprises for each rigid rod a dedicated recess or chamber for storing the respective rigid rod within the rod magazine, and in that the means for contamination protection comprise a sealing film that covers for each rigid rod the corresponding recess or chamber in which the rigid rod is stored within the rod magazine. A “chamber” is also referred to as compartment or storage cavity herein. Two sealing films may be arranged at or near a top surface and at or near a bottom surface of the rod magazine, whereby each rigid rod is arranged within a recess or compartment or storage cavity that is aligned parallel to a longitudinal axis of the rod magazine that extends from the top surface to the bottom surface of the rod magazine. Thus, each rigid rod can be pushed out of the corresponding recess or compartment or storage cavity by perforating only a small part of the top sealing film and of the bottom sealing film that is at or near the corresponding recess or compartment or storage cavity and that is required for removing the corresponding rigid rod from the rod magazine. Other parts of the top sealing film and of the bottom sealing film remain intact and continue to provide a tight sealing of other rigid rods. It is also possible to provide for a number of sealings whereby each sealing is dedicated to a corresponding rigid rod. Furthermore, it is also possible that the means for contamination protection comprise mechanical components like e.g. swiveling flaps, displaceable sliders or elastic tongues.

[0039] The means for contamination protection can also be designed as means for tamper evidence that provide for proof of originality of the rigid rods that are covered or sealed by the means for contamination protection.

[0040] According to an advantageous aspect of the invention, the rod conveyance means comprise a displaceably mounted piston that can be displaced through the guide tube along a rod axis of the rigid rod. Due to the positive engagement of the piston with the end face of the rigid rod, there is no risk of any slack or uncontrolled slip during the displacement of the rigid rod. The displacement of the displaceably mounted piston can be precisely controlled and monitored, whereby the displacement of the piston equals the displacement of the rigid rod that is pushed by the piston. A linear displacement of the piston can be performed with great precision with different kinds of rod conveyance means that can operate with different functional principles already known to a person skilled in the art. Such functional principles include e.g. a mechanical engagement, such as with spindles or hydraulic pistons, or non-contact mechanisms, such as a magnetic drive.

[0041] In order to remove a single rigid rod from the rod magazine, the rod magazine may comprise rigid rod removal means like, e.g. a rigid rod ejection mechanism that can be activated and operated to displace a rigid rod through an outlet opening of the rod magazine.

[0042] According to a further aspect of the invention, the rod conveyance means comprise a displaceably mounted piston that can be displaced through the rod magazine along a rod axis of the rigid rod. Thus, the rod magazine does not require any kind of internal ejection mechanism for rigid rods that are stored within the rod magazine. It is possible to provide for two separate displaceably mounted pistons, whereby a first piston is dedicated for displacing rigid rods out of the rod magazine, and a second piston is dedicated for conveying the rigid rod through the guide tube. However, it is also possible to make use of a single piston that can be operated and displaced to push a rigid rod out of the rod magazine and through the guide tube.

[0043] According to a favorable embodiment of the invention, the heating device is arranged at or near the discharge nozzle in a heat transmitting contact with the guide tube. The heating device can be a resistance heater with a heating cable or with a heating structure with an ohmic resistance that generates heat if an electric current is forced to flow through the heating cable or heating structure. Such heating devices and corresponding control devices are commercially available and can be easily adapted and operated to provide for a well-defined heat transfer into the guide tube and thus to allow for a very precise heating of the rigid rod that is conveyed through the guide tube. It is also possible to make use of another method of operating the heating device like, e.g. pumping a heated fluid through a heating pipe or a heating structure that surrounds the guide tube.

[0044] According to yet another favorable embodiment of the invention, the additive manufacturing apparatus further comprises a cooling device that is arranged in a heat transmitting contact at a distance to the discharge nozzle in order to prevent a premature heating of the rigid rod by means of the heating device that is arranged between the cooling device and the discharge nozzle. The cooling device can be e.g. a heat pipe or a Peltier element. The cooling device is preferably arranged next to the heating device and opposite to the discharge nozzle of the guide tube along the guide tube, i.e. closer to an entry opening of the guide tube through which all rigid rods are displaced into and conveyed through the guide tube.

[0045] It is also possible to provide for a guide tube comprising two heat transferring sections along the longitudinal axis that are separated by a thermal insulation, whereby the cooling device is arranged in a first heat transferring section, i.e. an entry section that extends from the entry opening of the guide tube to the thermal insulation. Furthermore, the heating device is arranged in a second heat transferring section, i.e. a heated section that extends from the thermal insulation to the discharge nozzle. By providing the guide tube with a thermal insulation the two heat transferring sections can be separated at a precisely defined location and the heat transfer that is caused by the cooling device and by the heating device can be precisely performed and monitored with only minimal interference from the respective adjacent section of the guide tube. In order to reduce any unwanted friction exerted on the rigid rod passing the thermal insulation between the two sections of the guide tube, an inner wall of the guide tube can be coated with an adhesion reducing surface.

[0046] According to an advantageous aspect of the invention, the additive manufacturing apparatus further comprises means for relocating or manipulating the rod magazine in such a manner as to allow conveying a following rigid rod after the rigid rod through an entry opening of the guide tube into the guide tube. The rod magazine may be designed to store a number of rigid rods arranged along a straight line or along one or more concentric circles. The rod magazine can comprise a cuboid or cylindrical housing with a lid that can be removed for filling up the rod magazine with rigid rods. The rod magazine can comprise a suitably shaped magazine tray with a holder or a recess for each rigid rod. According to one embodiment, the magazine tray can be mounted within the rod magazine so as to be movable linearly or in a circle within the rod magazine housing. According to an alternative embodiment, the rod magazine housing can be releasably mounted within the additive manufacturing apparatus in such a manner as to be movable linearly or in a circle, depending on the arrangement of rigid rods within the rod magazine. Thus, by moving either the magazine tray within the rod magazine or the rod magazine housing within the additive manufacturing apparatus e.g. by a rod magazine controller, a next rigid rod within the rod magazine can be arranged next to the entry opening of the guide tube. Then, the next rigid rod can by conveyed out of the rod magazine and through the guide tube. The displacement of the next rigid rod with respect to the guide tube as well as the conveyance of the next rigid rod through the guide tube can be automatically performed without the need for any manual interaction.

[0047] The housing may also comprise two small openings adapted for entering a piston into the housing through one small opening and pushing out a rigid rod through the other small opening that is arranged preferably at an opposite side of the housing. It is also possible that the housing comprises an ejection mechanism that pushes a next rigid rod out of the corresponding holder or recess within the rod magazine and through the small opening within the rod magazine housing towards the guide tube.

[0048] According to a very advantageous aspect of the invention, the guide tube is removably mounted within the printer extruder head. Thus, in order to clean the additive manufacturing apparatus and in particular the printer extruder head, the guide tube can be completely removed and either be cleaned separately or be replaced by a new or refurbished guide tube. As the guide tube is the only part within the printer extruder head that is in direct contact with the rigid rods and thus with the composite material that is extruded by the printer extruder head, removing the guide tube results in a very fast and effective cleaning of the printer extruder head. Furthermore, in case that any residual composite material is not fully extruded, but remains within the printer extruder head, this residual composite material will stick to the guide tube and thus will be fully removed from the printer extruder head. It is also possible that the discharge nozzle of the printer extruder head is removably attached to the guide tube or to the printer extruder head such as to allow for a selective removal and replacement of the discharge nozzle if need arises or a cleaning of the printer extruder head is required.

[0049] According to yet another embodiment of the invention, the piston is removably mounted within the rod conveyance means. Also, the piston can be removed e.g. for maintenance or cleaning purposes. The piston can also be replaced e.g. simultaneously with a change between rigid rods with different composite material or in order to enable a very fast and effective cleaning. Thus, all parts of the additive manufacturing apparatus that will be in contact with rigid rods i.e. with composite material can be designed to be removably mounted within the additive manufacturing apparatus which allows for effective and safe cleaning procedures in full compliance with quality regulations and standards like the Good Manufacturing Practices that apply for the manufacturing of pharmaceutical solid administration forms with active pharmaceutical ingredients.

[0050] In yet another aspect of the invention, the additive manufacturing apparatus further comprises a weighing means for measuring a total weight of the layer arrangement that has been deposited on the printer bed during or after manufacturing of the 3D item. This allows for determining the amount of composite material that has been deposited onto the printer bed either after the 3D item has been fully generated or at intervals during the manufacture process. Determination of the weight of the composite material that has been extruded can be compared with other methods for determining the amount of composite material that has been extruded, e.g. determining the length of a rigid rod that has been conveyed through the guide tube and deposited as viscous composite material onto the printer bed. It is possible that the weighing means comprise a weighing device that is arranged below the printer bed and continuously weighs the printer bed and all composite material that will be deposited onto the printer bed. In order to achieve a high precision of weighing results, the determination of a weight value is performed during an interval with approximately no movement within the additive manufacturing apparatus and in particular with no extrusion of viscous composite material from the printer extruder head.

[0051] Brief description of the drawings

[0052] The present invention will be more fully understood, and further features will become apparent, when reference is made to the following detailed description and the accompanying drawings. The drawings are merely representative and are not intended to limit the scope of the claims. In fact, those of ordinary skill in the art may appreciate upon reading the following specification and viewing the present drawings that various modifications and variations can be made thereto without deviating from the innovative concepts of the invention. Like parts depicted in the drawings are referred to by the same reference numerals.

[0053] Fig. 1 illustrates a schematic cross-sectional representation of an additive manufacturing apparatus for additive manufacturing of a 3D item by means of fused deposition modeling,

[0054] Fig. 2 illustrates an enlarged cross-sectional view of a printer extruder head,

[0055] Fig. 3 illustrates a perspective view of a rod magazine that can be inserted into the additive manufacturing apparatus shown in Fig. 1 ,

[0056] Fig. 4 illustrates a perspective view of a cylindrical magazine tray with a number of recesses arranged along a circumference of a circle, whereby a rigid rod can be stored in each of the recesses,

[0057] Fig. 5 illustrates a schematic explosive view of the rod magazine shown in Fig. 3 with the cylindrical magazine tray shown in Fig. 4.,

[0058] Fig. 6 illustrates a perspective view of a rod magazine with means for contamination protection, and

[0059] Fig. 7 illustrates a schematic cross-sectional view of the rod magazine shown in Fig. 6 along the plane VII-VII in Fig. 6.

[0060] Fig. 1 schematically illustrates an additive manufacturing apparatus 1 for additive manufacturing of a 3D item 2 on a printer bed 3. The additive manufacturing apparatus 1 comprises a printer extruder head 4 that is arranged within a manufacturing chamber 5 inside a housing of the additive manufacturing apparatus 1 that is not shown in Fig. 1 . The printer extruder head 4 is mounted stationary within the manufacturing chamber 5. In order to relocate the printer extruder head 4 with respect to the printer bed 3, the printer bed 3 comprises a printer bed plate 6 that can be displaced in all spatial directions. According to another embodiment of the additive manufacturing apparatus 1 , the printer extruder head 4 can be displaced with respect to a printer bed 3 that is mounted stationary within the manufacturing chamber 5. Furthermore, it is also possible to arrange both, the printer extruder head 4 and the printer bed 3, in a displaceable manner within the manufacturing chamber 5, which might be helpful in reducing the total processing time for the manufacturing of the 3D item 2.

[0061] Below the printer bed plate 6 there is a flexible cover 7 made of a film or a fabric that extends from below the printer bed plate 6 to a base plate that is not shown in Fig. 1 , but forms a bottom of the manufacturing chamber 5. The flexible cover 7 prevents any contamination of an interior of the manufacturing chamber 5 from a displacement device that is used for displacing the printer bed plate 6 during the manufacturing process of the 3D item 2. Furthermore, the flexible cover 7 is mounted in a detachable manner which allows easy removal of a flexible cover 7 after the manufacture of the 3D item 2 and inserting a new or cleaned flexible cover 7 to avoid any contamination of a new manufacturing process with residual composite matter from the printer extruder head 4 or with impurities e.g. from the displacement device that is used for displacing the printer bed 3 during the previous manufacturing process.

[0062] The printer extruder head 4 is mounted below a top plate 8 of the manufacturing chamber 5. The printer extruder head 4 is illustrated in more detail in Fig. 2 and will be described in more detail below. Above the top plate 8 there is a rod magazine 9 that holds a number of rigid rods 10 that can be subsequently fed into the printer extruder head 4. Each rigid rod 10 is made out of a composite material that is used for manufacturing of the 3D item 2. The rod magazine 9 can be inserted into the additive manufacturing apparatus 1 to provide for a number of rigid rods 10 for use in one or more manufacturing processes for manufacturing one or more 3D items 2. The rod magazine 9 can be removed from the additive manufacturing apparatus 1 to be reloaded with rigid rods 10 and to be inserted again into the additive manufacturing apparatus 1 in case that either all rigid rods 10 have been removed out of the rod magazine 9 or that a different kind of rigid rods 10, i.e. another composite material is required for continuing with the manufacturing of already started or new 3D items 2. The rod magazine 9 is illustrated in more detail in Figs 3 to 5 and will be described in more detail below.

[0063] Above the rod magazine 9 there is a rod conveyance means 11 arranged within the additive manufacturing apparatus 1. The rod conveyance means 11 comprises a piston 12 that can be linearly displaced along a rod axis of a rigid rod 10 that is stored within a cylindrical magazine tray 13 within the rod magazine 9. By displacing the piston 12 of the rod conveyance means 11 , the piston 12 positively engages with the rigid rod 10 and the piston 12 pushes the rigid rod 10 out of a corresponding recess or chamber within the magazine tray 13. Additional displacement of the piston 12 then pushes the rigid rod 10 through an entry opening 14 of a guide tube 15 and into the guide tube 15 that is part of the printer extruder head 4. Further displacement of the piston 12 then pushes the rigid rod 10 to a discharge nozzle 16 of the guide tube 15 at an opposite end of the guide tube 15, where the rigid rod 10 is heated and melted with the help of a heating device 17. Still further displacement of the piston 12 and the rigid rod 10 through the guide tube 15 then pushes a corresponding volume of the melted composite material out of the discharge nozzle 16 of the guide tube 15 and onto the printer bed 3. By moving the printer bed 3 with respect to the printer extruder head 4 during a continuous extrusion of melted composite material out of the discharge nozzle 16 of the printer extruder head 4, a layer arrangement of extruded and subsequently solidified composite material can be manufactured that forms the 3D item 2.

[0064] The printer extruder head 4 is shown in more detail in Fig. 2. The printer extruder head 4 comprises the guide tube 15 that is removably mounted within a tube holding structure 18. The guide tube 15 extends from the tube holding structure 18 towards a cooling device 19 and the heating device 17 that are arranged along a longitudinal axis of the guide tube 15. The cooling device 19 comprises a cooling block 20 through which run channels 21 through which a coolant can flow. The heating device 17 comprises a heating structure 22 with an ohmic resistance that generates heat if an electric current is forced to flow through the heating structure. The heating device 17 is arranged next to the discharge nozzle 16 of the guide tube 15 and in a heat transmitting contact with the guide tube 15. Thus, during operation of the heating device 17 a heated section 23 of the guide tube 15 will be heated and this also heats the rigid rod 10 pushed through it. In order to avoid any unwanted heat transfer along the guide tube 15 in the direction of the entry opening 14 of the guide tube 15 that might cause an uncontrolled increase in heating with the duration of the manufacturing process, the cooling device 19 is arranged between the entry opening 14 of the guide tube 15 and the heating device 17. During operation of the cooling device 19, an entry section 24 of the guide tube 15 that extends from the entry opening 14 to the heated section 23 with the heating device 17, will be cooled in such a manner as to counteract any unwanted or undefined heat transfer from the heating device 17 towards the entry opening 14 of the guide tube 15. In order to further reduce any unwanted thermal transfer along the longitudinal axis of the guide tube 15, the guide tube 15 comprises a thermal insulation 25 between the entry section 24 and the heated section 23.

[0065] The thermal insulation 25 can be designed as a circumferential tapering of the guide tube 15. According to another possible embodiment, the guide tube 15 comprises two guide tube sections made of a heat transmitting material like e.g. a metal, that are connected with each other via a ring made of a thermal insulating material like e.g. a synthetic foam material. An inner side of the guide tube 15 may be provided with a coating to reduce an unwanted adherence of residual material from the rigid rods 10.

[0066] The guide tube 15 can be fully removed from the printer extruder head 4. For this, the guide tube 15 can be detached from the tube holding structure 18, and the guide tube 15 can be extracted from the heating device 17 and from the cooling device 19. Thus, at predefined intervals or after each manufacturing process or before any change of type of rigid rods 10 that are conveyed through the guide tube 15, the guide tube 15 used up to that point can be removed and replaced by a new guide tube 15 or by a thoroughly cleaned guide tube 15.

[0067] Figs. 3 to 5 illustrate several different views of the rod magazine 9 that is used for storing many rigid rods 10 and for making the rigid rods 10 easily available during an automated manufacturing process performed by the additive manufacturing apparatus 1. The rod magazine 9 comprises the cylindrically shaped magazine tray 13 with a number of recesses 26 arranged along a circumference in the lateral surface of the magazine tray 13, whereby each recess 26 is aligned in the longitudinal direction and designed to store one rigid rod 10. The magazine tray 13 is rotatably mounted between a base 27 and a cover ring 28 that are fastened together by a handle element 29 of the rod magazine 9. The magazine tray 13 is freely rotatable between the base 27 and the cover ring 28.

[0068] The cover ring 28 allows for easy access to an engagement element 30 within the interior of the magazine tray 13. Thus, when inserted into the operating position above the top plate 8 of the additive manufacturing apparatus 1 , a driving and positioning device 31 of the rod conveyance means 11 can be operated to positively engage with the engagement element 30 of the magazine tray 13 in order to rotate the magazine tray 13 in such a manner as to position a given recess 26 above an opening 32 within the top plate 8 that is in alignment with the guide tube 15 of the printer extruder head 4. Then, by operating the piston 12 of the rod conveyance means 11 , the rigid rod 10 stored in said recess 26 that is positioned above and in alignment with the guide tube 15 can be pushed into and through the guide tube 15 by a linear displacement of the piston 12.

[0069] The recesses 26 of the magazine tray 13 are closed on a top side by the cover ring 28 and on a bottom side by the base 27. However, both the cover ring 28 and the base 27 comprise a reach-through opening 33, 34 that allows for the piston 12 to be linearly displaced through the reach-through opening 33 of the cover ring 28 and to push a rigid rod 10 out of the corresponding recess 26 and through the reach-through opening 34 of the base 27. All other recesses 26 remain closed at least by the base 27 to prevent any other rigid rods 10 to exit the magazine tray 13.

[0070] A recess cover 35 made of an elastic material can be arranged along the lateral surface of the magazine tray 13 to cover and lock all recesses 26, thereby forming a closed storage channel for storing the rigid rods 10 within the recesses 26. According to another embodiment, the recesses 26 are formed by longitudinal storage tubes arranged along a circumference of the magazine tray 13.

[0071] Figs. 6 and 7 illustrate a similar embodiment of the rod magazine 9 with the magazine tray 13 that is rotatably mounted between the base 27 and the cover ring 28. However, between the magazine tray 13 and the cover ring 28 there is a top sealing film 36 that covers a top surface of the magazine tray 13 and provides for a means for contamination protection 37. In a similar manner, between the magazine tray 13 and the base 27 there is a bottom sealing film 38 that covers a bottom surface of the magazine tray 13 and also provides for a means for contamination protection 37 of the rigid rods 10 that are stored within dedicated recesses 26 between the top sealing film 36 and the bottom sealing film 38.

[0072] In order to remove a rigid rod 10 from the respective recess 26, the piston 12 of the rod conveyance means 11 is linearly displaced along the rod axis of the rigid rod 10 and enters the rod magazine 9 through the reach-through opening 33 of the cover ring 28 and perforates the top sealing film 36. Then, the piston 12 pushes the rigid rod 10 along the respective longitudinal axis of the rigid rod 10 an of the corresponding recess 26 towards the bottom surface of the magazine tray 13, thereby forcing the rigid rod 10 to perforate the bottom sealing film 38 and to exit the rod magazine 9 through the reach-through opening 34 of the base 27, as schematically illustrated in Fig. 7. Even though the corresponding rigid rod 10 is removed from the rod magazine 9, other rigid rods 10 that remain stored in other recesses 26 remain protected by the means for contamination protection 37, i.e. by the top sealing film 36 and the bottom sealing film 38 that remains unperforated and fully intact at both ends of the other recesses 26 of the other rigid rods 10 that are still within the rod magazine 9.

[0073] Reference numbers:

[0074] 1 additive manufacturing apparatus

[0075] 2 3D item

[0076] 3 printer bed

[0077] 4 printer extruder head

[0078] 5 manufacturing chamber

[0079] 6 printer bed plate

[0080] 7 flexible cover

[0081] 8 top plate

[0082] 9 rod magazine

[0083] 10 rigid rod(s)

[0084] 11 rod conveyance means

[0085] 12 piston

[0086] 13 magazine tray

[0087] 14 entry opening

[0088] 15 guide tube

[0089] 16 discharge nozzle

[0090] 17 heating device

[0091] 18 tube holding structure

[0092] 19 cooling device

[0093] 20 cooling block

[0094] 21 channels

[0095] 22 heating structure

[0096] 23 heated section

[0097] 24 entry section

[0098] 25 thermal insulation

[0099] 26 recess

[0100] 27 base

[0101] 28 cover ring 29 handle element

[0102] 30 engagement element

[0103] 31 driving and positioning device

[0104] 32 opening 33 reach-through opening of the cover ring

[0105] 34 reach-through opening of the base

[0106] 35 recess cover

[0107] 36 top sealing film

[0108] 37 means for contamination protection 38 bottom sealing film

Claims

C L A I M S1 . Method for additive manufacturing of a 3D item (2) by means of fused deposition modeling of a composite material, whereby the composite material is fed through a heated printer extruder head (4) and deposited on a printer bed (3) as a layer arrangement that form the 3D item (2), characterized in that the composite material is provided as at least one rigid rod (10) that is conveyed out of a rod magazine (9) that is capable of storing at least one rigid rod (10), and in that the rigid rod (10) is then conveyed through a guide tube (15) that is arranged within the printer extruder head (4), whereby the rigid rod (10) is heated during the conveyance through the guide tube (15), and whereby the heated and viscous composite material is discharged through a discharge nozzle (16) at one end of the guide tube (15) and deposited as the layer arrangement onto the printer bed (3) to generate the 3D item (2).

2. Method according to claim 1 , characterized in that the rigid rod (10) is pressed out of the rod magazine (9) with a piston (12) that is displaced along a rod axis of the rigid rod (10).

3. Method according to claim 1 or claim 2, characterized in that the rigid rod (10) is conveyed through the guide tube (15) by either displacing a piston (12) or a subsequently conveyed following rigid rod along a guide tube axis of the guide tube (15).

4. Method according to any of the preceding claims, characterized in that the rod magazine (9) comprises means for contamination protection (37) for each rigid rod (10) that is stored within the rod magazine (9), whereby before conveying the rigid rod (10) out of the rod magazine (9) the respective means for contamination protection (37) that correspond to said rigid rod (10) are breached or removed to allow for accessing and removing said rigid rod (10) out of the rod magazine (9).

5. Method according to any of the preceding claims, characterized in that the heating of the rigid rod (10) is performed by heating the guide tube (15) at or near the discharge nozzle (16) by means of a heating device (17) that is arranged in a heat transmitting contact with the guide tube (15).

6. Method according to claim 5, characterized in that the guide tube (15) is cooled at a distance to the discharge nozzle (16) in order to prevent a premature heating of the rigid rod (10) that is conveyed through the guide tube (15).

7. Method according to any of the preceding claims, characterized in that in order to convey a following rigid rod (10) after the rigid rod (10) through the guide tube (15), the rod magazine (9) is relocated or manipulated in such a manner as to arrange the following rigid rod (10) next to an entry opening (14) of the guide tube (15) and to convey the following rigid rod (10) through the entry opening (14) of the guide tube (15) into the guide tube (15).

8. Method according to any of the preceding claims, characterized in that the guide tube (15) is removed and a clean following guide tube (15) is inserted into the printer extruder head (4) or that the discharge nozzle (16) is removed and a clean following discharge nozzle (16) is inserted into the printer extruder head (4) before conveying a following rigid rod (10) out of the rod magazine (9) and through the following guide tube (15).

9. Method according to any of the preceding claims 2 to 8, characterized in that the piston (12) is removed and a clean following piston (12) is used for pressing a following rigid rod (10) out of the rod magazine (9).

10. Method according to any of the preceding claims, characterized in that a total weight of the layer arrangement that has been deposited on the printer bed (3) is measured, preferably before conveying a following rigid rod (10) out of the rod magazine (9) and through the guide tube (15) or through the following guide tube11 . Method according to any of the preceding claims, characterized in that the method is used to generate a pharmaceutical solid administration form as 3D item (2), whereby the pharmaceutical solid administration form comprises at least one active pharmaceutical ingredient.

12. Additive manufacturing apparatus (1) for additive manufacturing of a 3D item (2) by means of fused deposition modeling of a composite material, the additive manufacturing apparatus (1) comprising a printer bed (3) and a printer extruder head (4) for discharging and depositing the heated composite material as a layer arrangement on a printer bed (3) to generate the 3D item (2) out of the composite material, whereby the discharging and depositing of the heated composite material can be controlled by a control device, the additive manufacturing apparatus (1 ) further comprising a heating device (17) for heating the composite material prior to discharging the heated composite material out of the printer extruder head (4), characterized in that the additive manufacturing apparatus (1 ) comprises a rod magazine (9) that is capable of storing at least one rigid rod (10), in that the printer extruder head (4) comprises a guide tube (15) through which a rigid rod (10) made of the composite material can be conveyed and heated by the heating device (17), and in that the additive manufacturing apparatus (1) comprises a rod conveyance means (11 ) for conveying a rigid rod (10) out of the rod magazine (9) and through the guide tube (15) before discharging the heated and viscous composite material through a discharge nozzle (16) at one end of the guide tube (15) in order to deposit the discharged composite material as the layer arrangement on the printer bed (3) to generate the 3D item (2).

13. Additive manufacturing apparatus (1 ) according to claim 12, characterized in that the rod magazine (9) is capable of storing at least two rigid rods (10), preferably more than 50 rigid rods (10) and most preferably more than 100 rigid rods (10).

14. Additive manufacturing apparatus (1 ) according to claim 12 or claim 13, characterized in that the rod magazine (9) comprises means for contamination protection (37) for each rigid rod (10) that is stored within the rod magazine (9).

15. Additive manufacturing apparatus (1 ) according to claim 14, characterized in that the rod magazine (9) comprises for each rigid rod (10) a dedicated recess (26) or chamber for storing the respective rigid rod (10) within the rod magazine (9), and in that the means for contamination protection (37) comprise a sealing film (36, 38) that covers for each rigid rod (10) the corresponding recess (26) or chamber in which the rigid rod (10) is stored within the rod magazine (9).

16. Additive manufacturing apparatus (1 ) according to claim 15, wherein each rigid rod (10) is separately sealed and removable from the rod magazine (9) without affecting the sealing of another rigid rod (10) that is also stored within the rod magazine (9).

17. Additive manufacturing apparatus (1 ) according to claim 15 or 16, wherein two sealing films (36, 38) are arranged at or near a top surface and at or near a bottom surface of the rod magazine (9), whereby each rigid rod is (10) arranged within a recess (26) or compartment or storage cavity that is aligned parallel to a longitudinal axis of the rod magazine that extends from the top surface to the bottom surface of the rod magazine.

18. Additive manufacturing apparatus (1 ) according to any of the claims 12 to 17, characterized in that the rod conveyance means (11 ) comprise a displaceably mounted piston (12) that can be displaced through the guide tube (15) along a rod axis of the rigid rod (10).

19. Additive manufacturing apparatus (1 ) according to any of the claims 12 to 18, characterized in that the rod conveyance means (11 ) comprise a displaceably mounted piston (12) that can be displaced through the rod magazine (9) along a rod axis of the rigid rod (10).

20. Additive manufacturing apparatus (1 ) according to any of the claims 12 to 19, characterized in that the heating device (17) is arranged at or near the discharge nozzle (16) in a heat transmitting contact with the guide tube (15).

21. Additive manufacturing apparatus (1 ) according to claim 20, characterized in that the additive manufacturing apparatus (1 ) further comprises a cooling device (19) that is arranged in a heat transmitting contact at a distance to the discharge nozzle (16) of the guide tube (15) in order to prevent a premature heating of the rigid rod (10) by means of the heating device (17) that is arranged between the cooling device (19) and the discharge nozzle (16).

22. Additive manufacturing apparatus (1 ) according to any of the claims 12 to 21 , characterized in that that the additive manufacturing apparatus (1 ) further comprises means for relocating or manipulating the rod magazine in such a manner as to allow to conveying a following rigid rod (10) after the rigid rod (10) through an entry opening (14) of the guide tube (15) into the guide tube (15).

23. Additive manufacturing apparatus (1 ) according to any of the preceding claims 12 to 22, characterized in that the guide tube (15) and / or the discharge nozzle (16) is removably mounted within the printer extruder head (4).

24. Additive manufacturing apparatus (1 ) according to any of the preceding claims 18 to 23, characterized in that the piston (12) is removably mounted within the rod conveyance means (11 ).

25. Additive manufacturing apparatus (1 ) according to any of the preceding claims 12 to 24, characterized in that the additive manufacturing apparatus (1 ) further comprises a weighing means for measuring a total weight of the layer arrangement that has been deposited on the printer bed (3) during or after manufacturing of the 3D item (2).

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